Mechanism comprised of ultrasonic lead screw motor

ABSTRACT

An optical assembly that contains an optical device movably attached to a apparatus for driving a threaded shaft assembly. The apparatus contains of a threaded shaft with an axis of rotation and, engaged therewith, a threaded nut. The assembly contains a device for subjecting the threaded nut to ultrasonic vibrations and thereby causing said the shaft to simultaneously rotate and translate in the axial direction.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation-in-part of applicant's co-pendingapplication U.S. Ser. No. 10/918,041, filed on Sep. 13, 2004, which inturn is a continuation in-part of U.S. Ser. No. 10/657,325, filed onSep. 8, 2003. The content of each of the aforementioned patentapplications is hereby incorporated by reference into thisspecification.

FIELD OF THE INVENTION

An imaging device and syringe pump device that contain a miniatureultrasonic linear motor assembly comprised of a threaded shaft and,engaged, therewith, a nut.

BACKGROUND OF THE INVENTION

Transducers using piezoelectric electrostrictive, electrostatic, orelectromagnetic technologies are very useful for precise positioning atthe nanometer scale. In the case of a piezoelectric device, the ceramicis formed into a capacitor that changes shape when charged anddischarged creating a force transducer or position actuator. When usedas a position actuator, the shape change of the piezoelectric ceramic isapproximately proportional to the applied voltage. Piezoelectricactuators are limited in range to about 0.1 percent of the length of theceramic which corresponds to typical stroke lengths of tens ofmicrometers. While the high stiffness and nanometer precision ofpiezoelectric actuators is very useful, more stroke is needed for manyapplications.

Numerous piezoelectric motor designs have been developed to “rectify”small ceramic shape changes and generate longer stroke.

A PZT stepping motor is described in U.S. Pat. No. 3,902,084; the entiredisclosure of this United States patent is hereby incorporated byreference into this specification. This motor uses aclamp-extend-clamp-retract operating sequence to add together many shortPZT actuator cycles. This stepping linear actuator operates atfrequencies from DC to several kilohertz, which produces loud noise andvibration. Position is not maintained when power is off. Resolutionbetter than one nanometer is achieved over 200 millimeters of travel.

A PZT inertial stick-slip motor is described in U.S. Pat. No. 5,410,206;the entire disclosure of this United States patent is herebyincorporated by reference into this specification. This motor rotates afine-threaded shaft using a split nut, which forms “jaws” that grip theshaft on opposite sides. A PZT actuator rapidly moves the jaws inopposite directions with an asymmetric alternating current drive signal.Fast jaw movements overcome the clamping friction and create slippage.Slower jaw movements do not slip and rotate the shaft. This stick-slipmotor makes similar noise and vibration as the above stepping motor butmoves 100 times slower and holds position when power is turned off.Resolution better than 50 nanometers is achieved over 25 millimeters oftravel.

Ultrasonic motors use piezoelectric-generated vibrations to createcontinuous movement with high speed, high torque, small size and quietoperation.

One of the earliest ultrasonic piezoelectric motors is described in U.S.Pat. No. 3,176,167; the entire disclosure of this United States patentis hereby incorporated by reference into this specification. Thisunidirectional rotary motor uses a quartz crystal oscillator to move athin rod and drive a ratchet wheel with the objective of driving a clockmechanism.

An example of a standing wave ultrasonic motor is described in U.S. Pat.No. 5,453,653; the entire disclosure of this United States patent ishereby incorporated by reference into this specification. This motoruses a rectangular PZT plate to generate ultrasonic oscillations of acontact point that is preloaded against a moving surface. The electrodepattern on the PZT plate is connected to an alternating current signaland generates two-dimensional oscillations of the contact tip with therequired amplitude and phase to generate a net force against the matingsurface. This ultrasonic motor is quiet and 100 times faster than astepping motor while producing about one third of the force. Generallyultrasonic motors are difficult to stop and start which limitsprecision. An encoder with closed-loop control is typically required toachieve sub-micrometer resolution.

A device for driving a threaded rod using ultrasonic vibrations isdescribed, e.g., in U.S. Pat. No. 6,147,435 of Katsuyuki Fujimura; theentire disclosure of this patent is hereby incorporated by referenceinto this specification. This patent discloses and claims: “ . . . Amechanism for driving a screw rod by supersonic vibration, comprising: ascrew rod provided with a groove portion formed helically along an axialdirection thereof; a pair of stands rotatably holding opposite ends ofsaid screw rod; a work rack partially surrounding said screw rod andslidable in the axial direction of said screw rod; at least one firstscrew rod rotation device secured on one side of said work rack andextending from said work rack to said screw rod, said at least one firstscrew rod rotation device comprising a first vibrator contacting withsaid groove portion of said screw rod at a first specific angle, a firstspring urging said first vibrator toward said groove portion of saidscrew rod at a specific pressure and a first piezoelectric actuator forvibrating said first vibrator upon electrical activation to rotate saidscrew rod in a first rotational direction; and at least one second screwrod rotation device secured on another side of said work rack andextending from said work rack to said screw rod, said at least onesecond screw rod rotation device comprising a second vibrator contactingwith said groove portion of said screw rod at a second specific angleopposite said first specific angle, a second spring urging said secondvibrator toward said groove portion of said screw rod at a specificpressure and a second piezoelectric actuator for vibrating said secondvibrator upon electrical activation to rotate said screw rod in a seconddirection.”

The device of U.S. Pat. No. 6,147,435 requires both a “first screw rodrotation device” and a “second screw rod rotation device”; these areillustrated in FIG. 3, e.g., as elements 16 a′ and 16 d′ (which comprisesuch first screw rod rotation device), and as elements 16 b′ and 16 c′(which comprise such second screw rod rotation device). Referring againto U.S. Pat. No. 6,147,435, when elements 16 a′ and 16 d′ are activatedby ultrasonic vibration, the screw rod 2 is caused to rotate in onedirection; and when elements 16 b′ and 16 c′ are activated by ultrasonicvibration, the screw rod 2 is caused to rotate in the oppositedirection.

The elements 16 a′/16 d′, and 16 b′/16 c′ are never activatedsimultaneously; to do so would waste energy and cause the screw rod 2 toremain stationary.

However, even when such elements 16 a′/16 d′ and 16 b′/16 c′ are notactivated simultaneously, there is a waste of energy. The inactive pairof elements still are contiguous with the threads on screw rod 2 and,thus, cause drag friction.

This drag friction is a problem with the device of U.S. Pat. No.6,147,435. As is described in claim 2 of the patent, and in order tosomewhat solve this problem, with the device of such patent “ . . . whenone of said first and second piezoelectric actuators is electricallyactivated, a very small amount of electric current is supplied to theother of said first and second piezoelectric actuators.” The efficiencyof the device of U.S. Pat. No. 6,147,435 is not very high.

It is an object of this invention to provide a mechanism for driving athreaded shaft by ultrasonic vibration that has a substantially higherefficiency than that of U.S. Pat. No. 6,147,435 while providing higherprecision, force, and speed than is typically achieved by otherultrasonic motors of a similar size.

It is another object of this invention to provide an imaging device anda syringe pump device comprised of the aforementioned mechanism fordriving a threaded shaft.

SUMMARY OF THE INVENTION

In accordance with this invention, there is provided an optical assemblycomprised of an optical element connected to an apparatus for driving athreaded shaft assembly, wherein said apparatus for driving a threadedshaft assembly is comprised of a threaded shaft and, engaged therewith,a nut. The assembly contains means for subjecting said nut to ultrasonicvibration and thereby causing said shaft to simultaneously rotate andtranslate in the axial direction. The assembly also is comprised ofmeans for applying an axial force upon said shaft.

In accordance with this invention, there is also provided a fluid pumpassembly comprised of a syringe with the plunger of said syringeconnected to a threaded shaft assembly comprised of a threaded shaftand, engaged therewith, a nut. The assembly contains means forsubjecting said nut to ultrasonic vibration and thereby causing saidshaft to rotate and said plunger to translate in the axial direction.

This invention also provides a mechanical motion stop mechanism thatstops movement of the threaded motor shaft at a desired point using atangent contact that stops rotation without locking together the threadsof the motor shaft and nut.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by reference to this specification, theappended claims, and the drawings, wherein like numerals refer to likeelement, and wherein:

FIGS. 1 through 6 show a motor containing four rectangular piezoelectricplates wherein FIG. 1 is a perspective view of such motor,

FIG. 2 is an exploded view of such motor,

FIG. 3 is an end view of such motor,

FIG. 4 shows the electrical connections to such motor,

FIG. 5 is cross sectional view of motor taken along lines A-A (30) ofFIG. 3, FIG. 5A shows a magnified scale view (47 on FIG. 5) of thethread engagement with external preload and the motor off, FIG. 5B showthe same magnified scale view in FIG. 5A with the motor operating, and

FIG. 6 is a cross section view taken along lines B-B (32) of FIG. 3;

FIGS. 7 through 12 illustrate a motor containing four piezoelectricstacks wherein:

FIG. 7 is a perspective view of such motor,

FIG. 8 is an exploded view of such motor,

FIG. 9 is an end view of such motor,

FIG. 10 shows the electrical connections to such motor,

FIG. 11 is cross section view taken along lines A-A (48) of FIG. 9, and

FIG. 12 is cross section view taken along lines B-B (46) of FIG. 9;

FIGS. 13 through 17 illustrate a motor containing a piezoelectric tubewith four outer electrodes wherein:

FIG. 13 is a perspective view of such motor,

FIG. 14 is an exploded view of such motor,

FIG. 15 is an end view of such motor,

FIG. 16 shows the electrical connections to such motor, FIG. 17 is crosssectional view taken along lines A-A (56) of FIG. 15;

FIG. 18 is a schematic illustration of the orbital movement of threadednut for the motor of FIG. 1 showing the rotation and translation of thethreaded shaft;

FIG. 19 is a schematic illustration of the electrical drive signalsrequired to create the movements shown in FIG. 18;

FIG. 20 through 25 show applications of the motor of FIG. 1 packaged andintegrated with linear stages, wherein: FIG. 20 is a perspective view ofthe motor assembly,

FIG. 21 is an exploded view of the motor assembly,

FIG. 22 is a cross section view of the motor assembly,

FIG. 23A is a perspective view of the motor assemble with a reverse viewfrom FIG. 20, FIG. 23B is a perspective view that illustrates of how themotor assembly rotates and translates in the forward direction, FIG. 23Cis a perspective view that illustrates how the motor assembly rotatesand translates in the reverse direction,

FIG. 24A shows the motor assembly integrated in a linear stage operatingin the forward direction, FIG. 24B shows the motor assembly integratedin a linear stage operating in the reverse direction and

FIG. 25 shows the motor assembly integrated in a three-axis stagesystem;

FIGS. 26 through 29 illustrate a motor containing a piezoelectric tubewith four outer electrodes which is similar to FIGS. 13 through 17wherein: FIG. 26 is a perspective view of such motor,

FIG. 27 is an exploded view of such motor,

FIG. 28 is an end view of such motor,

FIG. 29 is cross sectional view taken along lines A-A (130) of FIG. 28.

FIGS. 30 through 36 illustrate a motor containing four piezoelectricstacks in a planar arrangement wherein: FIG. 30 is a perspective view ofsuch motor,

FIG. 31 is an exploded view of such motor,

FIG. 32 is an end view of such motor,

FIG. 33 is cross section view taken along lines A-A (132) of FIG. 32,

FIG. 34 shows the electrical connections to a single piezoelectric stackin such motor,

FIG. 35 shows the electrical connections to the four stacks in suchmotor, and

FIG. 36A through 36E are a schematic illustration of the orbitalmovement of threaded nut for such motor of FIG. 30 showing the rotationof the threaded shaft, which is similar to the dynamic operation shownin FIG. 18.

FIGS. 37 through 42 illustrate an optical alignment mechanismintegrating a motor and lens wherein: FIG. 37 is a perspective view ofthe motor in FIG. 26 with a hollow shaft with a lens installed insidesaid shaft,

FIG. 38 is an end view of such motor,

FIG. 39 is a cross section view taken along lines A-A (134) of FIG. 38,

FIG. 40 is a perspective view of the motor in FIG. 30 with a hollowshaft with a lens installed inside said shaft,

FIG. 41 is an end view of such motor, and

FIG. 42 is a cross section view taken along lines A-A (136) of FIG. 41;

FIGS. 43 through 45 illustrate a camera auto focus and auto zoomassembly integrating two optical alignment mechanisms shown in FIG. 40with an focal plane imaging device wherein: FIG. 43 is a perspectiveview of the camera assembly,

FIG. 44 is an end view of such assembly, and

FIG. 45 is a cross section view taken along lines A-A (138) of FIG. 44;

FIGS. 46 through 48 illustrate a camera assembly, as shown in FIG. 43,where the optical lens are mounted on bearings with anti-rotation pinsso that the lens translate but do not rotate wherein: FIG. 46 is aperspective view of the camera assembly,

FIG. 47 is an end view of such assembly, and

FIG. 48 is a cross section view taken along A-A (140) of FIG. 47;

FIG. 49 through 52 illustrate a motor, (similar to FIGS. 1 through 5),containing four rectangular piezoelectric plates fixedly attached to acentral member whose entire internal length is comprised of engagedthread, wherein: FIG. 49 is a perspective view of such motor,

FIG. 50 is an exploded view of such motor,

FIG. 51 is an end view of such motor,

FIG. 52 is a cross sectional view of motor taken along lines A-A (246)of FIG. 51;

FIG. 53 through 59B show an application of the motor of FIG. 49 packagedand integrated within an optical assembly providing automatic focus asused in digital cameras and mobile phones, wherein: FIG. 53 is aperspective view of the motor assembly packaged in an automatic focuslens assembly,

FIG. 54 is a partial section view of the motor assembly package,

FIG. 55 is an exploded view of the motor assembly package,

FIG. 56 is a partial section view that depicts the motor assembly andthe accompanying lens mechanism fully retracted,

FIG. 57 is a partial section view illustrating how the motor assemblytranslates in a forward direction thus moving the lens mechanismaccordingly,

FIG. 58 is a partial section view demonstrating how the motor assemblycan fully translate and maneuver the lens mechanism,

FIG. 59A, a perspective view showing the motor assembly package of FIG.53 integrated in a mobile phone, FIG. 59B is a magnified partial sectionscale view of the motor assembly package (247 on FIG. 59A);

FIG. 60 through 66 exhibit an application of the motor of FIG. 26packaged and integrated within a dispensing syringe providing a meansfor controlled fluid dispensing as employed in medical fluid pumps,wherein: FIG. 60 is a perspective view of the motor assembly packaged ina syringe fluid dispensing system,

FIG. 61 is a partial section view of the motor assembly package,

FIG. 62 is an exploded view of the motor assembly package,

FIG. 63 is a perspective view detailing the motor assembly fullyretracted along with the plunger of the syringe, allowing fluid volumeto remain internal to the syringe body,

FIG. 64 is a perspective view of the motor assembly fully translatedwith its accompanying plunger, forcing all fluid volume from the syringebody,

FIG. 65 is a perspective view of the motor assembly packaged within amedical fluid pump,

FIG. 66 is a partial section view of FIG. 65 showing the motor assemblywithin the medical fluid pump housing; and

FIG. 67A through 71D illustrate a tangent motion limiting feature thatcan be utilized on all motors contained herein, FIG. 67A shows aperspective view of a typical motor assembly with integrated tangentmotion limiting feature in a non-engaged state, FIG. 67B is a magnifiedscale view of the tangent motion limiting feature (259 on FIG. 67A),

FIG. 68A shows a perspective view of a typical motor assembly withintegrated tangent motion limiting feature in an engaged state, FIG. 68Bis a magnified scale view of the tangent motion limiting feature (266 onFIG. 68A),

FIG. 69A is a perspective view of the stationary aspect of the tangentmotion limiting feature, FIG. 69B is a side view detailing thestationary characteristic of the tangent motion limiting feature,

FIG. 70A is a perspective view of the revolving aspect of the tangentmotion limiting feature, FIG. 70B is a side view detailing the revolvingcapacity of the tangent motion limiting feature,

FIG. 71A through 71D depicts the stages of operation of the tangentmotion limiting feature as the motor rotates and translates.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the first part of this specification, applicant will describe aminiature ultrasonic linear motor. In the second part of thisspecification, applicant will describe an optical assembly comprised ofan optical device connected to such motor.

In one embodiment of this invention, a miniature ultrasonic linear motorrotates a lead screw to produce linear movement. A cylinder supports athreaded nut with a first bending mode resonant frequency in theultrasonic range. The cylinder and nut are excited at this resonantfrequency by transducers that cause the nut to orbit at the end of thecylinder. The transducers may be piezoelectric, electrostrictive,electrostatic, electromagnetic or any device that can stimulate theresonant vibration. At least two transducers are required tosimultaneously excite the orthogonal bending modes of the cylinder witha plus or minus 90-degree phase shift and create a circular orbit. Aclose-fitting threaded shaft is installed inside the nut. A resilientaxial load is applied to the shaft through a low friction coupling. Thenut orbits at its resonant frequency, and the shaft's inertia keeps itcentered. The orbit of the nut generates torque that rotates the shaftand creates linear movement. At least two alternating current drivesignals are required for the transducers. The drive frequency mustexcite the mechanical frequency and control phase to achieve a circularnut orbit. Modulation of drive signal amplitude and duration controlvelocity. Phase shift between the drive signals may be positive ornegative, which reverses the direction of the nut orbit and the shaftrotation/translation. This embodiment, and other preferred embodiments,will be described in greater detail in the remainder of thisspecification.

Without wishing to be bound to any particular theory, applicant believesthat the operating principle of one of his ultrasonic linear actuatorsis the excitation of the first bending resonance of a cylindrical tube,which causes one or both ends of the tube to orbit around thecylindrical axis without rotating. In this embodiment, one end of thetube houses a threaded nut that also orbits around a mating threadedshaft and imparts a tangential force via friction thus rotating thethreaded shaft as it orbits. The friction in the threads is helpfulbecause it directly drives the screw. This is in strong contrast toconventional lead screw drives, where the thread contact friction isparasitic and creates windup, backlash and slow response. Anothersignificant advantage of helical threads used in this embodiment is thedirect conversion of rotation to translation with large mechanicaladvantage, which magnifies axial force and reduces linear speed and, asa result, increases precision.

In this embodiment, a transducer both either within or outside of theload path is preferably used to excite the first bending mode. Examplesof transducers that can be used are, e.g., piezoelectric elements andstacks, magnetostrictive materials, and electrostatic materials to namea few. This list does not include all transducer materials, but itshould be understood that any such material or mechanism that could beused to excite the first bending resonance of a cylindrical tube orsimilarly shaped block and achieve the orbit of one or both tube ends isembodied in this patent. The embodiments described herein usepiezoelectric material but could just as easily be embodied with analternate transducer material described above.

Referring to FIGS. 1 through 6, and in the preferred embodiment depictedtherein, an ultrasonic linear motor 10 is depicted. In the embodimentdepicted, four rectangular piezoelectric plates are used to generateultrasonic vibrations. In another embodiment, not shown in FIG. 1, othermeans may be used to generate ultrasonic vibrations.

As used in this specification, the term ultrasonic refers to anoperating frequency in excess of 20,000 Hertz. In one embodiment, theoperating frequency is at least about 25,000 Hertz. In anotherembodiment, the operating frequency is at least about 50,000 Hertz. Inyet another embodiment, the operating frequency is at least about100,000 Hertz.

As used in this specification, the term linear motor refers an actuatorthat produces movement in a substantially straight line by generatingforce and/or displacement. Reference may be had, e.g., to U.S. Pat. Nos.5,982,075 (ultrasonic linear motor), 5,134,334 (ultrasonic linearmotor), 5,036,245 (ultrasonic linear motor), 4,857,791 (linear motor),and the like. The entire disclosure of each of these United Statespatents is hereby incorporated by reference into this specification.

Referring again to FIGS. 1 through 6, and in the preferred embodimentdepicted therein, it will be seen that a threaded shaft 12 with aspherical ball tip 26 rotates and produces axial force and motion

The threaded shaft 12 is preferably movably disposed within a housing14. The length 15 of threaded shaft 12 (see FIG. 5) preferably exceedsthe length 13 of housing 14 by at least about 10 millimeters. In oneembodiment, length 15 exceeds length 13 by at least 25 millimeters. Inanother embodiment, length 15 exceeds length 13 by at least 50millimeters.

In one embodiment, the threaded shaft 12 has a first natural frequencythat is less than about 0.2 times as great as the first naturalfrequency of the housing 14. In another embodiment, the first naturalfrequency of the threaded shaft 12 is less than about 0.1 times as greatas the first natural frequency of the housing 14.

As used herein, the term first natural frequency refers to frequency ofthe first normal mode of vibration; see, e.g., page 1253 of theMcGraw-Hill Dictionary of Scientific and Technical Terms, Fourth Edition(McGraw-Hill Book Company, New York, N.Y., 1989. Reference also may behad to pages 5-59 to 5-70 (“Natural Frequencies of Simple Systems) ofEugene A. Avallone et al.'s “Mark's Standard Handbook for MechanicalEngineers” (McGraw-Hill Book Company, New York, N.Y., 1978). Referencealso may be had to U.S. Pat. Nos. 6,125,701, 6,591,608, 6,525,456,6,439,282, 6,170,202, 6,101,840, and the like; the entire disclosure ofeach of these United States patents is hereby incorporated by referenceinto this specification.

In the embodiment depicted in the Figures, an orbital movement of nut 16is created by the presence of two normal modes of vibration that areacting orthogonal to each other in planes parallel to the axiscenterline (see FIG. 2), as is best illustrated in FIG. 18. These twoorthogonal normal modes of vibration are provided by the interaction ofthe activated transducers (such as, e.g., plates 18, 20, 22, and 24) andthe housing 14; and such interaction causes orbital movement of the nut16 which, in turn, causes rotation and translation of threaded shaft 12.

In one embodiment, the first natural resonance frequency of nut 16 ispreferably at least five times as great as the operating frequency ofmotor assembly 10. It is thus preferred that nut 16 be a substantiallyrigid body.

In one embodiment, the threaded shaft 12 is fabricated from metal thatis substantially stainless steel. In this embodiment, the threaded shaft12 engages with a threaded nut 16 which, is fabricated from metal thatis substantially brass.

As will be apparent, it is preferred to use combinations of materialsfor the threaded shaft 12 and the threaded nut 16 so that abrasion andgalling are minimized. Other combinations of materials that will alsominimize such abrasion and galling may be used in the invention.

Referring again to FIG. 1, it will be seen that threaded shaft 12 iscomprised of a multiplicity of threads 17, preferably in the form of ahelical groove. In one embodiment, the threads 17 have a pitch lowerthan about 250 threads per inch and, preferably, less than about 200threads per inch. In another embodiment, the threads 17 have pitch lowerthan about 100 threads per inch. In one aspect of this embodiment, thethreads 17 have a pitch of from about 40 to about 80 threads per inch.

The threads 17 are preferably engaged with interior threads 19 of nut16, as is best illustrated in FIG. 18(also see FIG. 36). In onepreferred embodiment, the pitch of interior threads 19 is substantiallyequal to the pitch of exterior threads 17.

Although, for the purposes of simplicity of illustration, the threads 17and 19 are shown totally engaged, (except for FIGS. 5A, 5B, 18 and 36)there is preferably a diametrical clearance between threads 17 and 19 ofless than about 0.5 times the thread depth 33/35 of threads 17 and/orthreads 19. This diametrical clearance is best illustrated in FIG. 5A.Means for determining this diametrical clearance are well known.Reference may be had, e.g., to U.S. Pat. Nos. 6,145,805, 5,211,101,4,781,053, 4,277,948, 6,257,845, 6,142,749, and the like; the entiredisclosure of each of these United States patents is hereby incorporatedby reference into this specification. Reference also may be had, e.g.,to pages 8-9 et seq. (“Machine Elements”) of the aforementioned “MarksStandard Handbook for Mechanical Engineers.”

Referring to FIG. 5A, one preferred mode of engagement between threads17 and 19 is illustrated. As will be seen from this Figure, each ofthreads 17 has a tip 29, and each of threads 19 has a tip 31.Additionally, each of threads 17 and 19 has a thread depth, 33 and 35,respectively.

Referring again to FIG. 1, and in the preferred embodiment depictedtherein, it will be seen that rotation of the threaded shaft 12 isproduced by ultrasonic orbits of the threaded nut 16 connected to avibrating housing 14. In the embodiment depicted, the threaded nut 16 ispreferably connected to the housing 14. This is best illustrated in FIG.2.

Referring to FIG. 2, and in the preferred embodiment depicted therein,it will be seen that nut 16 is disposed within orifice 11. The nut 16 issecured within orifice 11 by conventional means such as, e.g., a pressfit, and/or adhesive means, etc.

In the preferred embodiment depicted in FIGS. 1 and 2, nut 16 is acylindrical nut. In another embodiment, not shown, nut 16 is a polygonalnut that may have a square shape, a hexagonal shape, an octagonal shape,etc.

Referring again to FIGS. 1 and 2, and in the preferred embodimentdepicted therein, it will be seen that a multiplicity of ceramic plates18 et seq. are attached to the outside surface 37 of the housing 14.

It is preferred that the ceramic plates 18 et seq. change theirrespective lengths upon being subjected to a electrical voltage and, inparticular, to a change in electrical voltage. As used therein, and asis described elsewhere in this specification, these ceramic plates maybe described as “active ceramic plates.” In one embodiment, the activeceramic plates 18 et seq. are selected from the group consisting ofpiezoelectric plates, electrostrictive plates, and mixtures thereof. Forthe sake of simplicity of discussion, the embodiments of at least FIGS.1 and 2 will be described with reference to piezoelectric plates.

In the embodiment depicted in FIG. 2, four piezoelectric plates 18, 20,22, and 24 are bonded to the outside surface 37 of the housing andgenerate the nut 16 orbital vibrations when excited by alternatingelectrical drive signals on electrodes 21 and 23 on each piezoelectricplate (see FIG. 4).

In one embodiment, only two such piezoelectric plates are used, plates18 and 20. In another embodiment, eight or more piezoelectric plates areused. Regardless of how many such piezoelectric plates are used, asufficient number of such plates are used to excite motion in orthogonalplanes 39 and 41 (see FIG. 2).

For the sake of simplicity of representation, four piezoelectric plates18, 20, 22, and 24 will be discussed. These plates are preferably bondedto the corresponding exterior surfaces 37 of housing 14 so that theplates are completely contiguous with such exterior surfaces 37.

The piezoelectric plates 18 et seq. are connected to a source ofelectrical voltage by electrodes 21 and 23, as is best shown in FIG. 4.As will be apparent, and for the sake of simplicity of representation,the connection of electrodes 21 and 23 is shown only with reference topiezoelectric plate 20, it being understood that comparable connectionsare made with respect to the other piezoelectric plates.

Referring to FIG. 4, and to the preferred embodiment depicted therein,it will be seen that all four inside electrodes 23 are connected toground 25. In this embodiment, the piezoelectric material is a commonlyavailable “hard” composition with low dielectric losses and highdepoling voltage. Thus, for example, one may use a piezoelectricmaterial sold as “PZT-4” by the Morgan Matroc company of Bedsford, Ohio.This preferred material typically has several important properties.

Thus, the preferred material preferably has a dielectric loss factor ofless than about 1 percent at a frequency greater than about 20,000 Hertzand, preferably, less than about 0.5 percent. In one embodiment, thedielectric loss factor is about 0.4 percent at a frequency greater thanabout 20,000 Hertz.

Thus, the preferred material has a d33 piezoelectric charge coefficientof at least about 250 picoCoulomb/Newton's and, preferably, at leastabout 270 picoCoulomb/Newton's. In one embodiment, the preferredmaterial has a d33 piezoelectric charge coefficient of about 285picoCoulomb/Newton's.

Thus, the preferred material has a d31 piezoelectric charge coefficientof at least about −90 picoCoulomb/Newton's and, more preferably, atleast about −105 picoCoulomb/Newton's. In one embodiment, the d31piezoelectric charge coefficient is about −115 picoCoulomb/Newton's.

In one embodiment, the preferred material is a single crystal materialwith a d33 piezoelectric charge coefficient of at least about 2500picoCoulomb/Newton's, and a d31 piezoelectric charge coefficient of atleast about 900 picoCoulomb/Newton's

For a discussion of some suitable materials, and by way of illustrationand not limitation, reference may be had, e.g., to U.S. Pat. Nos.3,736,532 and 3,582,540. The entire disclosure of each of these UnitedStates patents is hereby incorporated by reference into thisspecification.

By way of further illustration, and as is known to those skilled in theart, low dielectric-loss piezoelectric materials are known to thoseskilled in the art. Reference may be had, e.g., to U.S. Pat. No.5,792,379 (low-loss PZT ceramic composition); the entire disclosure ofthis United States patent is hereby incorporated by reference into thisspecification.

In one embodiment, the piezoelectric material is a single crystalpiezoelectric material. These materials are known in the art. Referencemay be had, e.g., to U.S. Pat. Nos. 5,446,330, 5,739,624, 5,814,917,5,763,983 (single crystal piezoelectric transformer), 5,739,626,5,127,982, and the like. The entire disclosure of each of these UnitedStates patents is hereby incorporated by reference into thisspecification.

Referring again to FIG. 4, and in the preferred embodiment depictedtherein, the axial length of the piezoelectric plates 18, 20, 22, and 24changes in proportion the applied voltage (Vx/86 and Vy/88) and the d₃₁piezoelectric charge coefficient.

As will be apparent, piezoelectric plates 18,22 and 20,24 work togetherin pairs, respectively, to bend the housing 14 (see, e.g., FIGS. 1 and2) and excite the orbital resonance. Alternating electric drive signals86 and 88 are preferably applied to plates 20,24 and 18,22,respectively, with poling directions 43. As is well known to thoseskilled in the art, poling directions 43 are the directions in which thedipoles in the piezoelectric material are aligned during manufacture.Reference may be had, e.g., to U.S. Pat. Nos. 5,605,659 (method forpoling a ceramic piezoelectric plate), 5,663,606 (apparatus for poling apiezoelectric actuator), 5,045,747 (apparatus for poling a piezoelectricceramic), and the like. The disclosure of each of these United Statespatents is hereby incorporated by reference into this specification.

For each plate pair 18, 22 and 20,24 the electric field is positive withrespect to the poling direction 43 on one plate and negative withrespect to the poling direction 43 on the opposite plate. Drive signalVx 86 is preferably applied to plates 20, 24 and produces simultaneousexpansion on one plate and contraction on the opposite plate and thusbends the housing 14 in the plane 39 (see FIG. 2), and in the Xdirection 72 a/72 b (see FIG. 18). In a similar manner the drive signalVy 88 is applied to plates 18,22 and bends the housing 14 in the plane41 (see FIG. 2), and in the Y direction 74 a/74 b (see FIG. 18).

The housing end 45 opposite the threaded nut 16 preferably supports aguide bushing 28 with a small clearance between the bushing insidediameter and the outside diameter of the threaded shaft 12 (see FIG. 2).The threaded shaft 12 supports a resilient axial force 27 (see FIGS. 5and 6) that is applied via the spherical ball tip 26 using a hard flatsurface that produces low friction.

It is preferred that, during the operation of the motor 10, the axialforce 27 that is preferably transmitted through ball 26 be from about0.1 to about 100 Newton's. As will be apparent, the axial force 27preferably is of similar magnitude to the output driving force.

The spherical ball 26 (see FIG. 2) is one means of coupling threadedshaft 12 to its load 27 (see FIG. 5) with low frictional torque. As willbe apparent to those skilled in the art, one may use other means forcoupling motion from a rotating threaded shaft to a moving load. Thus,e.g., one may use a rolling element bearing, one may use an arcuate loadcontiguous with a flat surface on threaded shaft 12, etc. Reference maybe had, e.g., to U.S. Pat. Nos. 5,769,554 (kinematic coupling method),6,325,351 (highly damped kinematic coupling for precision instruments),etc.; the entire disclosure of each of these United States patents ishereby incorporated by reference into this specification.

Referring to FIGS. 1 and 2, the end 45 of the housing 14 opposite thethreaded nut 16 incorporates flanges that are the connection point for astationary cover 58 (FIG. 21). The thread pitch on the shaft 12 and onthe nut 16 converts the orbital tangential force and movement to axialforce and movement. The pitch may be selected to optimize the forcemagnification, speed reduction, resolution enhancement and off-powerholding force.

Referring to FIGS. 7 through 12, and in the preferred embodimentdepicted therein, the ultrasonic linear motor 30 preferably uses fourpiezoelectric stacks 36, 40 and 42 (also see FIGS. 7 and 8) to generateultrasonic vibrations. A threaded shaft 12 with a spherical ball tip 26rotates and produces axial force and motion. The rotation is produced byan ultrasonic orbits of the threaded nut 16 connected to a vibratingcylinder 32. Four piezoelectric stacks 36, 38, 40, and 42 are bonded tothe end of the cylinder opposite the threaded nut and bonded to the basering 34. The four stacks 36 et seq. are constructed using well-knownassembly and electrical interconnection methods 44 with the inside stackleads preferably being connected together to a common ground 35. Theaxial length of the stacks 36 et seq. changes in proportion to theapplied voltage and the d33 piezoelectric charge coefficient. Thepiezoelectric material is a commonly available “hard” composition withlow dielectric losses and high depoling voltage. Alternating electricaldrive signals 86 and 88 are connected to the outside leads of eachpiezoelectric stack 44 and excite orbital vibrations of the nut.Piezoelectric stacks 36 and 40 and 38 and 42 work together in pairs,respectively, to rotate the tube and excite the orbital resonance.Alternating electric drive signals Vx 86 and Vy 88 are applied to stacks38, 42 and 36, 40, respectively, with poling directions 43. For eachstack pair 38, 42 and 36, 40, the electric field is positive withrespect to the poling direction 43 on one stack and negative withrespect to the poling direction on the opposite stack. Drive signal Vx86 is applied to stacks 38, 42 and produces simultaneous expansion onone stack and contraction on the opposite stack; and thus it rotates thetube in the X direction 72 a/72 b (see FIG. 18). In a similar manner,the drive signal Vy 88 is applied to stacks 36, 40 and moves the end ofthe tube in the Y direction 74 a/74 b (see FIG. 18). The base ring 34opposite the threaded nut 16 supports a guide bushing 28 with a smallclearance between the bushing inside diameter and the outside diameterof the threaded shaft. The threaded shaft 12 supports a compliant axialforce 27 that is applied via the spherical ball tip 26 using a hard flatsurface that produces low friction. The base ring 34 is the connectionpoint for a stationary cover 58 (FIG. 21). The thread pitch on the shaft12 and nut 16 converts the orbital tangential force and movement toaxial force and movement. The pitch may be selected to optimize theforce magnification, speed reduction, resolution enhancement andoff-power holding force.

Referring to FIGS. 13 through 17, the ultrasonic linear motor 50 uses apiezoelectric tube 54 with quadrant electrodes to generate ultrasonicvibrations. A threaded shaft 12 with a spherical ball tip 26 rotates andproduces axial force and motion. The rotation is produced by ultrasonicorbits of the threaded nut 16 connected to a vibrating piezoelectrictube 54. The inside diameter of the tube is a continuous electrode 61,which is grounded 63, and the outside diameter of the tube is dividedinto four separate electrodes 60, 62, 64, and 66. The piezoelectricmaterial is a commonly available “hard” composition with low dielectriclosses and high depoling voltage. The axial length of the portion of thepiezoelectric tube beneath each electrode 60, 62, 64, and 66 changes inproportion the applied voltage and the d₃₁ piezoelectric chargecoefficient. Electrode sections 60, 64 and 62, 66 work together in pairsrespectively to bend the tube 54 and excite the orbital resonance.Alternating electric drive signals 86 and 88 are applied to plates 60,64 and 62, 66, respectively, with poling directions 43. For eachelectrode pair 60, 64 and 62, 66, the electric field is positive withrespect to the poling direction on one electrode and negative withrespect to the poling direction on the opposite electrode. Drive signalVx 86 is applied to electrodes 60, 64 and produces simultaneousexpansion under one electrode and contraction under the oppositeelectrode; and thus it bends the tube in the X direction 72 a/72 b (seeFIG. 18). In a similar manner the drive signal Vy 88 is applied toplates 62, 66 and bends the tube in the Y direction 74 a/74 b (see FIG.18).

The tube end opposite the threaded nut 16 is bonded to a base flange 52and holds a guide bushing 28 with a small clearance between the bushinginside diameter and the outside diameter of the threaded shaft. Thethreaded shaft 12 supports a compliant axial force 27 that is appliedvia the spherical ball tip 26 using a hard flat surface that produceslow friction. The base flange is the connection point for a stationarycover 58 (FIG. 21). The thread pitch on the shaft 12 and nut 16 convertsthe orbital tangential force and movement to axial force and movement.The pitch may be selected to optimize the force magnification, speedreduction, resolution enhancement and off-power holding force.

Referring to FIGS. 18 and 19, the motor 10 (see FIG. 1) operation andcorresponding drive signals 86 and 88 used to effect such operation areshown (see also FIG. 36). The piezoelectric plate pairs work together,with one expanding 70 while the other simultaneously contracts 69, tobend the housing. The alternating drive signals Vx 86 and Vy 88 arepreferable sinusoidal with equal amplitude 90/91 and a ninety degreephase shift 92 to produce a circular orbit. A positive phase shift 92produces a positive nut 16 orbit direction and a positive shaft 12rotation 96/translation 98, while a negative phase shift 92 produces anegative orbit direction and a negative shaft rotation/translation. Asingle orbital cycle of the motor, for one direction of rotation, andthe corresponding drive signal amplitudes 90 and 91, are shownsequentially in ninety degree increments 76, 78, 80, 82 and 84. Thecylindrical bending and orbital movement is shown in the X 72 a/72 b andY 74 a/74 b directions. The nut contacts the side of the threaded shaftat one location 73 a with a clearance 73 b on the opposite side (seeFIG. 5B), whereby the contact imparts tangential force and movement thatcauses the shaft 12 to rotate 96 and translate 98 a small amount foreach orbital cycle. The amount of rotation and translation per cycledepends on many factors, including orbit amplitude, the magnitude of theforce 27 acting on the shaft, and the coefficient of friction andsurface finish of the threads. If a zero-slip condition is achievedbetween the contact 73 a of the nut and shaft, the movement per cycle isnominally proportional to the diametrical clearance between the threads.In general, as drive amplitudes 90 and 91 increase, the orbit diameterincreases, the normal contact force between the shaft 12 and nut 16increases, slippage decreases, speed increases, and torque/forceincreases.

The ultrasonic frequency is the inverse of the period (see periods 94 aand 94 b of FIG. 19); and such ultrasonic frequency is preferably thesame for both signals and matches the first bending resonant frequencyof the housing 14.

Referring to FIGS. 20 through 25 the motor assembly 100 is integratesmotor 10 with cover 58 and knurled knob 102. A threaded shaft 112 isdisposed within the motor 10. As is best shown in FIG. 21, the threadedshaft 112 is similar to threaded shaft 12 (see FIG. 1) but differstherefrom in having a smooth spindle 113 integrally attached thereto.The spindle 113 is adapted to be attached to knurled knob 102. Cover 58is attached to motor 10 at flange 45. Knurled knob 102 rotates andtranslates with shaft 112 without contacting cover 58.

FIG. 21 is an exploded view of motor assembly 100. FIG. 22 is asectional view of motor assembly 100.

FIGS. 23A, 23B and 23C illustrate the motor assembly 100. FIG. 23A is aperspective view of motor assembly 100 reversed from FIG. 20. FIG. 23Billustrates operation of motor assembly 100 with the knob 102 and shaft112 rotating clockwise 103 and translating in direction of arrow 105. Bycomparison, FIG. 23C illustrates operation of motor assembly 100 withthe knob 102 and shaft 112 rotating counter clockwise 107 andtranslating in direction of arrow 109.

As will be apparent, and for the sake of simplicity of representation,the physical means of electrical connection to the various components ofthe motor assemblies have been omitted from the Figures.

As will also be apparent, the presence of the knurled knob 102 allowsone to move the motor assembly 100 by manual means instead of or inaddition to moving such motor assembly 100 by electrical means. Thus,e.g., the assembly 100 can be used as a micrometer drive replacementthat will afford a user both the conventional means of manual adjustmentas well as the additional means of electrically automated adjustment.

In one embodiment, not shown, knurled knob 102 is mechanically connectedto an exterior motor to allow for a second means of mechanical movementof the assembly.

FIGS. 24A and 24B illustrate adjustable linear stages 106 that arecomprised of motor assemblies 100 operatively connected to lineartranslation stages 104 a/104 b. In this embodiment cover 58 of motorassembly 100 is attached to the bottom stage portion 104 b and ball 26is in contact with top stage portion 104 a. As will be apparent, whenknurled knob 102 moves in clockwise in direction 103, linear motion inthe direction of arrow 105 is produced. Conversely, when knurled knob102 is move counterclockwise in direction 107, linear motion in thedirection of arrow 109 is produced.

In one embodiment, illustrated schematically in FIGS. 24A and 24B, aspring assembly 111 comprised of pins 115 and 116 (shown in dotted lineoutline) biases translation stage 104 a/104 b in the direction of arrow109. In the embodiment depicted, pin 115 is attached to the top, movablepart 104 a of the assembly, and the pin 116 is attached to thestationary bottom part 104 b of the assembly. As will be apparent, thespring assembly 111 may be used to produce the axial force 27 (see FIGS.5 and 6).

FIG. 25 is a perspective view of a micromanipulator 120 that is capableof moving its stages 106 a, 106 b, and 106 c, in the X, Y, and Z axes.

Although the invention has been described in its preferred form with acertain degree of particularity, it is to be understood that the presentdisclosure of the preferred form can be changed in the details ofconstruction, and that different combinations and arrangements of partsmay be resorted to without departing form the spirit and the scope ofthe invention.

In the previous portions of this specification, there has been describedan apparatus for driving a threaded shaft assembly comprised of athreaded shaft with an axis of rotation and, engaged therewith, athreaded nut, wherein said assembly comprises means for subjecting saidthreaded nut to ultrasonic vibrations and thereby causing said shaft tosimultaneously rotate and translate in the axial direction. As will beapparent, one may produce a comparable device that is comprised of meansfor causing said threaded shaft assembly to vibrate, thereby causingsaid threaded nut to simultaneously rotate and translate.

FIGS. 26 through 29 are schematics of another preferred motor 142 of theinvention. Referring to FIGS. 26 through 29, the ultrasonic linear motor142 uses a piezoelectric tube 144 with quadrant electrodes to generateultrasonic vibrations. Motor 142 and tube 144 are similar to motor 50and tube 54. (Refer to FIGS. 13 through 17.) A threaded shaft 12 with aspherical ball tip 26 rotates and produces axial force and motion. Therotation is produced by ultrasonic orbits of the threaded nut 152connected to a vibrating piezoelectric tube 144. The inside diameter ofthe tube is a continuous electrode 61, which is grounded 63. Thedifference between tube 54 and tube 144 is electrode 61 wraps around theends of the tube and forms an electrode ring 146 on the outside diameterof each end. The outside diameter of the tube is divided into fourseparate electrodes 60, 62, 64, and 66. The piezoelectric material is acommonly available “hard” composition with low dielectric losses andhigh depoling voltage. The axial length of the portion of thepiezoelectric tube beneath each electrode 60, 62, 64, and 66 changes inproportion the applied voltage and the d31 piezoelectric chargecoefficient. Electrode sections 60, 64 and 62, 66 work together in pairsrespectively to bend the tube 144 and excite the orbital resonance. Aspreviously discussed for motor 50, alternating electric drive signals 86and 88 are applied to electrodes 60, 64 and 62, 66, respectively, withpoling directions 43. For each electrode pair 60, 64 and 62, 66, theelectric field is positive with respect to the poling direction on oneelectrode and negative with respect to the poling direction on theopposite electrode. Drive signal Vx 86 is applied to electrodes 60, 64and produces simultaneous expansion under one electrode and contractionunder the opposite electrode; and thus it bends the tube in the Xdirection 72 a/72 b (see FIG. 18). In a similar manner the drive signalVy 88 is applied to electrodes 62, 66 and bends the tube in the Ydirection 74 a/74 b (see FIG. 18).

Referring again to FIG. 26, the tube end opposite the threaded nut 152is bonded to a guide bushing 150 with a small clearance between thebushing inside diameter and the outside diameter of the threaded shaft.The mounting flange 148 is bonded to the outside diameter of the tube144 at the node point. The node point is the axial location on the tubethat has minimum movement when the tube is resonating. The thread pitchon the shaft 12 and nut 152 converts the orbital tangential force andmovement to axial force and movement. The pitch may be selected tooptimize the force magnification, speed reduction, resolutionenhancement and off-power holding force.

FIGS. 30 through 36 another preferred embodiment of the motor 154 ofthis invention. Referring to FIGS. 30 through 36, and in the preferredembodiment depicted therein, the ultrasonic linear motor 154 preferablyuses four piezoelectric stacks 162, 164, 166 and 168 oriented radiallyin a plane at 90 degree spacing to generate ultrasonic vibrations. Athreaded shaft 12 with a spherical ball tip 26 rotates and producesaxial force and motion. The rotation is produced by an ultrasonic orbitsof the threaded nut 156 connected to the four piezoelectric stacks 162,164, 166, and 168 via elastic elements 160 where said stacks are bondedto the base flange 158. The four stacks 162 et seq. are constructed frompiezoelectric plates 172 using well-established assembly and electricalinterconnection methods 170 with the leads preferably being connectedtogether to a common ground 174. The length of the stacks 162 et seq.changes in proportion to the applied voltage 69, 70 and the d33piezoelectric charge coefficient. The piezoelectric material is acommonly available “hard” composition with low dielectric losses andhigh depoling voltage. Alternating electrical drive signals 86 and 88are connected to the leads of each piezoelectric stack and exciteorbital vibrations of the nut. Piezoelectric stacks 162 et seq. worktogether in pairs, respectively, to move the nut 156 in an orbitalresonance 76, 78, 80, 82, 84. Alternating electric drive signals Vx 86and Vy 88 are applied to stacks 162,166 and 164,168 respectively, withpoling directions 176. For each stack pair 162,166 and 164,168 theelectric field is positive with respect to the poling direction 176 onone stack and negative with respect to the poling direction on theopposite stack. Drive signal Vx 86 is applied to stacks 162,166 andproduces simultaneous expansion on one stack and contraction on theopposite stack; and thus it translates the nut 156 in the X direction 72a/72 b. In a similar manner, the drive signal Vy 88 is applied to stacks164,168 and translates the nut 156 in the Y direction 74 a/74 b. Whilenot shown, it is understood by those skilled in the art that actuatorconfigurations, other than piezoelectric stacks 162 et seq., may also beused to produce the same orbital resonance of nut 156. Such actuatorsinclude piezoelectric plates that change length in proportion theapplied voltage and the d31 piezoelectric charge coefficient,electromagnetic solenoids or voice coils, electrostatic attraction, orother tranducers capable of producing ultrasonic frequency motion. Thethread pitch on the shaft 12 and nut 156 converts the orbital tangentialforce and movement to axial force and movement. The pitch may beselected to optimize the force magnification, speed reduction,resolution enhancement and off-power holding force.

FIGS. 37 through 39 illustrate an optical assembly 180 that is comprisedof one of the motors 142 of this invention. As will be apparent fromthese Figures, in the embodiment depicted the lens 184 is rotationallysymmetric with its centerline 204 coincident with 204 axis of rotationof the threaded hollow shaft 182.

Referring to FIGS. 37 through 39 and in the preferred embodimentdepicted therein, the optical alignment mechanism 180 integrates a motor142 with a shaft 182 that has a hollow center with an optical element184 aligned and bonded on the shaft centerline 204. The optical element184 can be of many types including transmissive, reflective, concave,convex or assemblies of multiple optical elements. The motor 142 causesthe hollow shaft 182 and optical element 184 to rotate and translate 202achieving precise optical alignment for functions such changing focallength or focusing.

In the embodiment depicted in FIGS. 37 through 39, an optical element184 is used. In this embodiment, the optical element is a lens. It ispreferred that the optical element 184 be a movable optical element. Onemay use many of the movable optical elements known to those skilled inthe art. Reference may be had, e.g., to U.S. Pat. Nos. 3,612,664(optical path compensating device); 3,958,117 (distance determining andautomatic focusing apparatus); 4,184,759 (photographic apparatus);4,629,308 (lens and shutter positioning mechanism for variablemagnification copier); 5,296,943 (multi-path electronic cameraassembly); 5,894,371 (focus mechanism for varifocal lens); 5,969,886(lens barrel and optical apparatus); 6,236,448 (projection exposuresystem); 6,445,514 (micro-positioning optical element); 6,606,426 (beamalignment systems); 6,678,240; and the like. The disclosure of each ofthese United States patent applications is hereby incorporated byreference into this specification.

By way of further illustration, one may use one or more of the linearmotors of this invention in prior art cameras that utilize prior artmotors. Thus, by way of illustration, one may replace the prior artmotor in one or more of the cameras described in U.S. Pat. No. 5,091,781(camera moving apparatus); 5,157,435 (automatic focusing apparatus for avideo camera); 5,357,308 (automatic zoom camera and driving methodthereof); 5,434,621 (object tracing device for automatic zooming);5,943,513 (camera zooming apparatus); and the like. The entiredisclosure of each of these United States patents is hereby incorporatedby reference into this specification.

FIGS. 40 through 42 illustrate another preferred optical assembly 186.Referring to FIGS. 40 through 42 and in the preferred embodimentdepicted therein, the optical alignment mechanism 186 integrates a motor154 with a shaft 182 that has a hollow center with an optical element184 aligned and bonded on the shaft centerline. The optical element 184can be of many types including transmission, reflective, concave, convexor assemblies of multiple optical elements. The motor 154 causes thehollow shaft 182 and optical element 184 to rotate and translate 202 oncenterline 204 achieving precise optical alignment for functions suchchanging focal length or focusing.

FIGS. 43 through 45 illustrate yet another preferred optical assembly188. Referring to FIGS. 43 through 45 and in the preferred embodimentdepicted therein, a camera auto-focus and auto-zoom assembly 188integrates two optical alignment mechanisms 194 and 196, similar tomechanism 186, with a focal plane imaging device 192 such as a CCD arrayand housing 190. Mechanism 196 is closest to the imaging device 192 andincorporates a transmission lens that changes the camera zoom bytranslating the lens 198 relative to device 192 and lens 200. In thisembodiment the zoom lens 198 diameter is larger than the imaging device192 and focus lens 200 so that mechanism 196 can translate withoutinterference. Mechanism 194 is adjacent to mechanism 196, oppositedevice 192, and incorporates a transmission lens that changes the camerafocus by translating the lens 200 relative to lens 198 and device 192.In this embodiment the diameter of the focus lens 200 is smaller thanthe zoom lens 198 to eliminate interference when translating mechanism194. The centerlines of optical elements 198 and 200 are coincident withcenterline 204 and perpendicular to the image plane of device 192.Elements 198 and 200 translate and rotate 202 simultaneously. In thisembodiment, elements 198 and 200 are rotationally symmetric aroundcenterline 204.

FIGS. 46 through 48 illustrate yet another preferred optical assembly206. Referring to FIGS. 46 through 48, and in the preferred embodimentdepicted therein, a camera auto-focus and auto-zoom assembly 206 withtranslating 208 but non-rotating optical lens 198 and 200 is describedfor situations where non-rotating optics is required. Said assembly 206is similar to assembly 188 with translating and rotating 202 opticallens 198 and 200 but incorporates lens mounting shafts 210 that areconnected to the threaded motor shafts 182 via a low friction rotarybearing 212 such as a ball bearing. A pin 214 is connected to the end ofeach mounting shaft 210 and oriented perpendicular to centerline 204.Said pin 214 engages a stationary slot 216 in housing 190 which preventsrotation of the pin 214, mounting shaft 210 and lens 198 and 200 butallows translation of the pin 214, mounting shaft 210 and lens 198 and200 in the axial direction 208 parallel to centerline 204.

As will be apparent to those skilled in the art, the optical assembliesillustrated in FIGS. 26 through 48 are merely illustrative of the manymovable optical elements with which applicant's linear motor may beutilized.

Referring to FIGS. 49 through 52 and the embodiment depicted therein,the motor 230 is similar to motor 10 depicted in FIGS. 1 through 5 and18, and is comprised of a motor body 235 upon which is a mounting flange231. It is preferred that the flange 231 be thin, preferably 0.25millimeters-0.50 millimeters thick and located as close as possible tothe nodal point of the first bending resonance of the motor 230 wherethe vibration amplitude is minimized. The motor body 235 contains alongitudinal threaded hole 235 a traversing the entire length throughwhich a threaded shaft 232 with corresponding threads passes such thatthe rounded rotation face 233 on shaft 232 protrudes from the threadedhole 235 a. In this embodiment the entire length of body 235 is threaded235 a. However, it is understood other embodiments may thread onlyportion of the body length and allow the remaining length to be a smoothclearance fit with the screw 232. Upon the motor body 235, rectangularpiezoelectric plates 18, 20, 22, and 24 are fixedly attached viaadhesion processes.

Referring to FIG. 50, it will be seen that the rectangular piezoelectricplates 18, 20, 22, and 24 are adhered to the flat mounting surfaces 235b of the motor body 235.

In the embodiment depicted in FIGS. 49 through 52, mounting flange 231has an outer radial profile 231 a and recesses 231 b that are of a sizeso not to obstruct the rectangular piezoelectric plates 18, 20, 22, and24, but can be of any profile so as to offer a variety of mountingoptions and accommodate various piezoelectric plate geometries as isbest illustrated in FIG. 54. The motor 230 electrically and mechanicallyoperates in the same manner as motor 10 (Refer to FIGS. 1 through 5, 18and 19) The motion caused by the excitation of the rectangularpiezoelectric plates 18, 20, 22 and 24 is the same as described formotor 10 and the subsequent bending of the motor body 235 causes thethreaded shaft 233 to rotate 260 a and effectually translate 260 blinearly.

Referring to FIGS. 53 through 59B, the motor 230 integrates with anoptical assembly 236. The optical assembly 236 can be of the nature ofan automatic focus module such that is found in commercial digitalimaging products such as cameras and mobile phones. Referring to FIG.53, motor 230 is encased by housing 237 and cover 238, and operates lensassembly 239 which accepts light through aperture 240. The housing 237and cover 238 may be comprised of injection molded plastics.

FIG. 54 represents a partial section view of the components of theoptical assembly 236. Light that enters the aperture 240 and proceedsthrough the lens 239 is imaged onto a sensor 241. Such sensors 241 mayinclude digital image sensors using CCD or CMOS technologies. The motor230 is fixedly attached to the housing 237 via the mounting flange 231.The mounting flange 231 can be located by molded features in the housing237 and secured via conventional commercial processes such as heatstamping. The threaded shaft 232 is allowed to rotate 260 a andsubsequently translate 260 b through a clearance hole 237 a. The roundedtip 233 of screw 232, obscured from view, rests against the upper lensflexure 242, providing a means to change the location of lens 239relative to sensor 241. Lens 239 is fixedly attached on one face to theupper lens flexure 242 and on the opposing face to lower lens flexure243 for form a four-bar linkage that guides the motion of lens 239 in anarc-linear motion 260 c that is substantially a straight-line motion forsmall amplitudes. The upper lens flexure 242 and lower lens flexure 243are constructed of a resilient material such a spring steel produced viacommercial processes such as photo-chemical etching or wire electricaldischarge machining. The members are pre-bent such that a preload force260 d is always exerted on the shaft tip 233. The upper lens flexure 242and lower lens flexure 243 are held apart by spacer 244 and inconjunction with the mounting of the lens 239 operation is such thattranslation of the threaded shaft 232 will produce a motion 260 c whichis best illustrated in FIGS. 56, 57 and 58.

Referring to FIG. 55, the optical assembly 236 is assembled in a mannerthat all components can be mounted sequentially from one direction. Thesensor 241 is installed in sensor receptacle 237 b of housing 237. Motor230 is fixedly attached to motor posts 237 d in the housing 237. Theupper lens flexure 242 and lower lens flexure 243 with spacer 244 areattached via adhesives or mechanical means such as press fitting to thelens 239. The spacer 244 is circumferentially fitted over spacer shaft237 c in housing 237. Orientation of the lens 239 may be maintained viaa locating flat 245 on the upper lens flexure 242 and a correspondingfeature on the spacer shaft 237 c. The cover 238 is installed onto coverledge 237 e in the housing 237.

Referring to FIGS. 56 through 58, operation of the embodiment isdetailed therein. FIG. 56 is a partial section view illustrating thethreaded shaft 232 fully retracted inside the clearance hole 237 a andthe pre-bent flexures 242 and 243 are exerting preload force 260 d ontothe rounded rotation face 233, not shown. Lens 239 has motion 260 c andmoved to a position closest to sensor 241. FIG. 57 is a partial sectionview illustrating the threaded shaft 232 having incurred some rotationalmotion 260 a and resultant translation 260 b, effectually liftingflexures 242 and 243 and producing motion 260 c which moves lens 239 toa position further away from sensor 241. FIG. 58 is a partial sectionview illustrating the threaded shaft 232 having incurred additionalrotational motion 260 a and resultant translation 260 b, producingmotion 260 c and moving lens 239 to its maximum distance from sensor241.

Referring to FIGS. 59A and 59B, it will be apparent that the opticalassembly 236 will be fitted into a mobile phone 248. For the sake ofsimplicity of representation, the physical means of electricalconnection to the various components of the optical assembly 236 andmobile phone 248 have been omitted from the figures.

Referring to FIGS. 60 through 66, motor 142 integrates with syringeassembly 249. The syringe assembly 249 can be one of commercial medicalavailability and used in the likeness of products such as wearable fluidpumps. FIG. 60 depicts a perspective view of the syringe assembly 249and embodied motor 142, best illustrated in FIG. 61. Motor 142 is housedin syringe plunger 251 engaged therewith syringe body 250. Threadedshaft 12 is circumferentially housed by rotational bearing 254 andfixedly accommodated in base 252. FIG. 61 is a partial section view ofsaid embodiment wherein motor 142 is engaged therewith the syringeplunger 251 such that operating motor 142 will cause threaded shaft 12to rotate 260 a inside a low-friction bearing 254. The bearing 254allows shaft rotation but prevents the shaft 12 from translating 260 bwhich results in the motor housing 142 translating 260 b. Housing 142 isattached to syringe plunger 251, thus, motor 142 and housing 251translate 260 b together but do not rotate.

A Hall Effect rotational position sensor 256 is integrates in housing252 and measures the rotation of shaft 12. In this embodiment acommercial sensor is shown from Austria Microsystems Model AS5040Magnetic Rotary Encoder. It is understood that many other types ofposition sensors may be incorporated that use others sensing methodsincluding capacitance, inductance, optical and interferometry. Apermanent magnet 255 is bonded to the end of shaft 12 with the north andsouth poles on opposite semicircles. As shaft 12 rotates the changingmagnetic field is measured by sensor 256 and the amount of rotationconverted to a digital electronics signal that transmitted by encodercircuit board 253.

Referring to FIG. 62, an explode view is illustrated. The encodercircuit board 253 and its mounted encoder 256 are assembled within thebase 252 therewith is mounted the rotational bearing 254. Magnet 255 ispermanently installed with the threaded shaft 12 with a fixed clearancefrom sensor 256. The syringe plunger 251 is circumferentially held withthe syringe body 250.

Referring to FIGS. 63 and 64, the operation of said embodiment isdetailed. FIG. 63 illustrates a fully retracted motor 142, best shown inFIG. 61, and syringe plunger 251, allowing for a vacuous area 257 withinthe syringe body 250 for which a voluminous fluid can occupy. FIG. 64illustrates a fully extended motor 142, best shown in FIG. 61, andsyringe plunger 251, causing an inhabitance of the vacuous area 257 ofFIG. 63 within the syringe body 250 and subsequent purging of any fluidwithin the syringe body 250.

Referring to FIGS. 65 and 66, it will be apparent that the syringeassembly 249 will be fitted into a commercial medical product such as afluid pump. For the sake of simplicity of representation, the physicalmeans of electrical connection to the various components of the encodercircuit board 253 and motor 142 have been omitted from the figures. Withspecific reference to FIG. 65, the syringe plunger nests within thefluid pump 258 such that anti-rotation tab 251 a engages tab rest 258 aas to prevent rotation of the syringe plunger 251 during motor 142operation.

Referring to FIG. 67A through 71D, a tangent motion limiting feature 261is described as the preferred method of mechanically limiting forwardand reverse travel in all embodiments without locking the threads. FIG.67A is a perspective view of the tangent motion limiting feature 261.The threaded shaft 12 is extended and end cap 264 and thumb knob 265 areseparated. Stationary tab 262 and revolving tab 263 are not engaged.FIG. 67B is a magnified scale view of the tangent motion limitingfeature 261 (259 on FIG. 67A). FIG. 68A is a perspective view of thetangent motion limiting feature 261. The threaded shaft 12 is retractedand end cap 264 and thumb knob 265 are in close proximity of each other.Stationary tab 262 and revolving tab 263 are engaged. FIG. 68B is amagnified scale view of the tangent motion limiting feature 261 (266 onFIG. 67A).

Referring to FIGS. 69A through 70B, components of the tangent motionlimiting feature 261 are illustrated. FIG. 69A is a perspective view ofthe end cap 264 and the stationary tab 262. FIG. 69B is a side view ofthe end cap 264 and the stationary tab 262. FIG. 70A is a perspectiveview of the thumb knob 265 and the revolving tab 263. FIG. 70B is a sideview of the thumb knob 265 and the revolving tab 263.

Referring to FIGS. 71A through 71D, the operation of the tangent motionlimiting feature 261 is detailed. FIG. 71A is a side view showing thethreaded shaft 12 extended; end cap 264 and thumb knob 265 areseparated. Stationary tab 262 and revolving tab 263 are not engaged.FIGS. 71B and 71C are side views wherein sequentially progressing, thethreaded shaft 12 begins to rotate 260 a and translate 260 b such thatthe end cap 264 and thumb knob 265 begin to approach each other.Stationary tab 262 and revolving tab 263 are not engaged. FIG. 71D is aside view wherein, the threaded shaft 12 has rotated 260 a andtranslated 260 b such that the end cap 264 and thumb knob 265 have met.Stationary tab 262 and revolving tab 263 are engaged and shaft 12 motionis stopped without creating high axial load on the threads andsubsequent locking that prevents motor operation.

The invention having been fully described, it will be apparent to thoseskilled in the art that many changes and modifications may be madethereto without departing from the spirit and scope of the appendedclaims.

1. An apparatus for driving a threaded shaft assembly comprised of athreaded shaft with an axis of rotation and, engaged therewith, athreaded nut, wherein said assembly is comprised of means for subjectingsaid threaded nut to ultrasonic vibrations and thereby causing saidthreaded shaft to simultaneously rotate and translate in the axialdirection through said nut, thus applying an axial force in said axialdirection.
 2. The apparatus as recited in claim 1, wherein said threadedshaft is operatively connected to a load in said axial direction.
 3. Theapparatus as recited in claim 2, wherein said load is moveable.
 4. Theapparatus as recited in claim 3, wherein said load is comprised of anoptical assembly comprised of a lens, an image sensor, and a flexure,wherein said flexure provides substantially linear guidance along theaxial direction of said lens relative to the location of said imagesensor.
 5. The apparatus as recited in claim 4, further comprising acamera comprised of said optical assembly.
 6. The apparatus as recitedin claim 5, wherein said axial force in said axial direction causes anoptical apparatus to move, wherein said optical apparatus is selectedfrom the group consisting of said lens, said image sensor, a zoominglens and combinations thereof.
 7. The apparatus as recited in claim 6,further comprising a phone, wherein said camera is disposed within saidphone.
 8. The apparatus as recited in claim 1, further comprised of asupport housing, wherein said threaded shaft is operatively connected toa low-friction bearing that allows rotation and prevents axial movementand said load is connected to said threaded nut and said supporthousing.
 9. The apparatus as recited in claim 8, wherein said load iscomprised of a movable plunger located in a syringe.
 10. The apparatusas recited in claim 1, further comprising means for measuring themagnitude of movement of said threaded shaft.
 11. The apparatus asrecited in claim 10, wherein said means for measuring the magnitude ofmovement of said threaded shaft is comprised of a Hall Effect magneticsensor.
 12. The apparatus as recited in claim 10, wherein the positionof said threaded shaft is measured using a sensor, wherein said sensoris selected from the group consisting of a capacitive sensor, aninductive sensor, an optical sensor, and combinations thereof.
 13. Theapparatus as recited in claim 9, further comprising a drug deliveryapparatus comprised of said syringe.
 14. The apparatus as recited inclaim 1, wherein said threaded shaft is operatively configured totranslate in both a positive axial direction and a negative axialdirection.
 15. The apparatus as recited in claim 14, further comprisinga tangent motion limiting feature wherein (a) said threaded nut and saidthreaded shaft are comprised of threads; (b) said tangent motionlimiting feature is configured so as to prevent said rotation withoutincreasing said axial load on said threads.
 16. The apparatus as recitedin claim 15, wherein said tangent motion limiting feature is comprisedof a first notch disposed on said threaded nut and a second notchdisposed on said threaded shaft, each of which are operativelyconfigured such that said first notch will engage said second notch,thus preventing said threaded nut and said threaded shaft fromtightening.
 17. The apparatus as recited in claim 1, further comprisingmeans for generating said ultrasonic vibrations.
 18. An apparatus fordriving a threaded shaft assembly comprised of a threaded shaft with anaxis of rotation and, engaged therewith, a threaded nut, wherein saidthreaded nut and said threaded shaft are operatively configured suchthat, upon exposure to ultrasonic vibrations, said threaded shift willsimultaneously rotate and translate in the axial direction through saidnut, thus applying an axial force in said axial direction.
 19. Anapparatus for driving a threaded shaft assembly comprised of a threadedshaft with an axis of rotation and, engaged therewith, a threaded nut,wherein: (a) said assembly comprises means for subjecting said threadednut to ultrasonic vibrations and thereby causing said threaded shaft tosimultaneously rotate and translate in the axial direction through saidnut, thus applying an axial force in said axial direction; (b) saidrotation and said translation in said axial direction through said nutoccurs over a distance greater than the amplitude of any singleamplitude of said ultrasonic vibration.
 20. The apparatus as recited inclaim 19, wherein said threaded shaft is operatively connected to a loadin said axial direction.
 21. The apparatus as recited in claim 20,wherein said load is comprised of a lens and a sensor wherein said axialforce in said axial direction causes a focusing element to move, whereinsaid focusing element is selected from the group consisting of saidlens, said sensor, and combinations thereof.
 22. The apparatus asrecited in claim 19, further comprising means for measuring themagnitude of motion of said threaded shaft.
 23. The apparatus as recitedin claim 19, wherein said load is comprised of a syringe.
 24. Theapparatus as recited in claim 15, wherein said threaded shaft has aproximal and distal end, wherein both said proximal and said distal endsare each comprised of said tangent motion limiting feature.